The Robotron KC series used an U880microprocessor, a clone of the Zilog Z80, which was clocked at 2.5 MHz. The keyboard was integrated into every machine. Software could be loaded from cassette tapes; a separate cassette deck was needed for doing so. All models featured module slots for up to four expansion modules, which allowed to expand the hardware, such as by upgrading the RAM or allowing to connect the KC to a printer, but also included applications and programming languages. The KC 87 had the BASICinterpreter in ROM, while in case of the earlier models, the user had to load it from tape or to use a BASIC expansion module. In addition to the home computers, Robotron also offered cassette tapes with applications and games, modules, and other equipment. However, the availability of the Robotron KC series for private customers was very limited. The computers were mostly used at educational institutions, organizations, and enterprises. Therefore, the extracurricular use of home computers was often allowed for students at institutions and organizations.[1]